Up-regulation of divalent metal transporter 1 in 6-hydroxydopamine intoxication is IRE/IRP dependent

Iron plays a key role in Parkinson＇s disease （PD）. Increased iron content of the substantia nigra （SN） has been found in PD patients, and divalent metal transporter 1 （DMT1） has been shown to be up-regulated in the SN of both MPTP-induced PD models and PD patients. However, the mechanisms underlying DMT1 up-regulation are largely unknown. In the present study, we observed that in the SN of 6-hydroxydopamine （6-OHDA）-induced PD rats, DMT1 with the iron responsive element （IRE, DMTI＋IRE）, but not DMT1 without IRE （DMTI-IRE）, was up- regulated, suggesting that increased DMTI＋IRE expression might account for nigral iron accumulation in PD rats. This possibility was further assessed in an in vitro study using 6-OHDA-treated and DMTl＋IRE-over-expressing MES23.5 cells. In 6-OHDA-treated MES23.5 cells, increased iron regulatory protein （IRP） 1 and IRP2 expression was observed, while silencing of IRPs dramatically diminished 6-OHDA-indueed DMTI＋IRE up-regulation. Pre- treatment with N-acetyl-L-cysteine fully suppressed IRPs up-regulation by inhibition of 6-OHDA-indueed oxidative stress. Increased DMTI＋IRE expression resulted in increased iron influx by MES23.5 cells. Our data provide direct evidence that DMTI＋IRE up-regulation can account for IRE/IRP-dependent 6-OHDA-induced iron accumulation initiated by 6-OHDA-induced intracellular oxidative stress and that increased levels of intracellular iron result in ag- gravated oxidative stress. The results of this study provide novel evidence supporting the use of anti-oxidants in the treatment of PD, with the goal of inhibiting iron accumulation by regulation of DMT1 expression.

Divalent metal transporter 1 expression and iron deposition in the substantia nigra of a rat model of Parkinson's disease

Extensive iron deposition has been observed in the midbrain substantia nigra （SN） of Parkinson＇s disease （PD） patients, but the mechanisms of iron deposition in the SN remain poorly understood. The present study investigated the relationship between dopaminergic neuronal damage, iron content changes, and divalent metal transporter 1 （DMT1） in the midbrain SN of PD rats to explore the relationship between time of iron deposition and DMT1 expression. Frozen midbrain SN sections from model rats were stained with Perls＇ iron. Results showed massive loss of tyrosine hydroxylase （TH）-positive cells in the SN and increased DMT1 expression in model group rats. No obvious iron deposition was observed in the SN during early stages after damage, but significant iron deposition was detected at 8 weeks post-injury. Results demonstrate that the loss of TH-positive cells in the SN appeared simultaneously with increased DMT1 expression. Extensive iron deposition occurred at 8 weeks post injury, which could be regarded as an early time window of iron deposition.

Changes in iron transporter divalent metal transporter 1 in proximal jejunum after gastric bypass

AIM: To describe the variation that divalent metal transporter 1 (DMT1) shows in patients after Roux-en-Y gastric bypass (RYGB) surgery.

Upregulation of Divalent Metal Transporter 1 (DMT1) Is Involved in Amyloid Precursor Protein Processing and Aβ Generation

The amyloid beta precursor protein (APP) and its pathogenic byproduct β-amyloid peptide (Aβ) play central roles in the pathogenesis of Alzheimer’s disease (AD). Reduction in

Influence of Iron Supplementation on DMT1(IRE)-induced Transport of Lead by Brain Barrier Systems in vivo

Objective To investigate the potential involvement of DMT1（IRE） protein in the brain vascular system in vivo during Pb exposure. Methods Three groups of male Sprague-Dawley rats were exposed to Pb in drinking water, among which two groups were concurrently administered by oral gavage once every other day as the low and high Fe treatment group, respectively, for 6 weeks. At the same time, the group only supplied with high Fe was also set as a reference. The animals were decapitated, then brain capillary-rich fraction was isolate from cerebral cortex. Western blot method was used to identify protein expression, and RT-PCR to detect the change of the m RNA. Results Pb exposure significantly increased Pb concentrations in cerebral cortex. Low Fe dose significantly reduced the cortex Pb levels, However, high Fe dose increased the cortex Pb levels. Interestingly, changes of DMT1（IRE） protein in brain capillary-rich fraction were highly related to the Pb level, but those of DMT1（IRE） m RNA were not significantly different. Moreover, the consistent changes in the levels of p-ERK1/2 or IRP1 with the changes in the levels of DMT1（IRE）. Conclusion These results suggest that Pb is transported into the brain through DMT1（IRE）, and the ERK MAPK pathway is involved in DMT1（IRE）-mediated transport regulation in brain vascular system in vivo.

Effective components of Chinese herbs reduce central nervous system function decline induced by iron overload

Abnormally increased levels of iron in the brain trigger cascade amplification in Alzheimer＇s dis- ease patients, resulting in neuronal death. This study investigated whether components extracted from the Chinese herbs epimedium herb, milkvetch root and kudzuvine root could relieve the abnormal expression of iron metabolism-related protein in Alzheimer＇s disease patients. An APPs,~JPSI^E9 double transgenic mouse model of Alzheimer＇s disease was used. The intragas- tric administration of compounds from epimedium herb, milkvetch root and kudzuvine root improved pathological alterations such as neuronal edema, increased the number of neurons, downregulated divalent metal transporter 1 expression, upregulated ferroportin 1 expression, and inhibited iron overload in the cerebral cortex of mice with Alzheimer＇s disease. These com- pounds reduced iron overload-induced impairment of the central nervous system, indicating a new strategy for developing novel drugs for the treatment of Alzheimer＇s disease.

Baicalin suppresses iron accumulation after substantia nigra injury: relationship between iron concentration and transferrin expression

Previous studies have shown that baicalin prevented iron accumulation after substantia nigra injury, reduced divalent metal transporter 1 expression, and increased ferroportin 1 expression in the substantia nigra of rotenone-induced Parkinson＇s disease rats. In the current study, we investigated the relationship between iron accumulation and transferrin expression in C6 cells, to explore the mechanisms of the inhibitory effect of baicalin on iron accumulation observed in Parkinson＇s disease rats. Iron content was detected using inductively coupled plasma-atomic emission spectroscopy. Results showed that iron content decreased 41% after blocking divalent metal transporter 1 and ferroportin 1 proteins. After treatment with ferric ammonium citrate of differing concentrations （10, 50, 100, 400 ktg/mL） in C6 glioma cells, cell survival rate and ferroportin 1 expression were negatively correlated with ferric ammonium citrate concentration, but divalent metal transporter 1 expression positively correlated with ferric ammonium citrate concentration. Baicalin or deferoxamine reduced divalent metal transporter 1 expression, but increased ferroportin 1 expression in the 100 μg/mL ferric ammonium citrate-loaded C6 cells. These results indicate that baicalin down-regulated iron concentration, which positively regulat- ed divalent metal transporter 1 expression and negatively regulated ferroportin 1 expression, and decreased iron accumulation in the substantia nigra.

Sodium glutamate and gamma-aminobutyric acid affect iron metabolism in the rat caudate putamen

Glutamic acid and gamma-aminobutyric acid （GABA） influence iron content in the substantia nigra and globus pallidus, although the mechanisms of action remain unclear. The present study measured iron content and changes in divalent metal transporter 1 （DMT1） and hephaestin expression in the substantia nigra and caudate putamen, and explored the effects of GABA and glutamic acid on iron metabolism. Results demonstrated that iron content and DMT1 non iron response element [DMT1 （-IRE）] expression were significantly greater but hephaestin expression was significantly lower in the caudate putamen of the monosodium glutamate group compared with the control group. No significant difference in iron content was detected between the GABA and control groups. DMT1 （-IRE） expression was significantly reduced, but hephaestin expressiori was significantly increased in the GABA group compared with the control group. In addition, there was no significant difference in tyrosine hydroxylase expression between monosodium glutamate and GABA groups and the control group. These results suggested that glutamate affected iron metabolism in the caudate putamen by increasing DMTI（-IRE） and decreasing hephaestin expression. In addition, GABA decreased DMT1 （-IRE） expression in the caudate putamen.

Expression and function of DMT1 without IRE in C6 cells mediated by recombinant adenovirus

Divalent metal transporter 1(DMT1)is a ferrous iron import protein.The improper expression of DMT1 is involved in neurodegenerative diseases.In the present study,we constructed a recombinant adenovirus containing the gene of DMT1 without the iron response element(DMT1-IRE)and investigated its expression and function in the C6 glioma cell line.The DMT1-IRE gene,obtained by RT-PCR,was cloned into the shuttle plasmid-ing pAdTrack-CMV containing greenfluorescent protein(GFP)reporter gene.Linearized plasmid pAdTrack-CMV-DMT1-IRE was subsequently co-transformed into Escher-ichia coli(E.coli)BJ5183 cells along with an adenoviral backbone plasmid pAdEasy-1 after digestion with Pme I.Pac I-digested pAdEasy1-DMT1-IRE was then transfected into E1-transformed human embryonic kidney cells(HEK293 cells),in which recombinant adenoviruses were generated within 7 to 10 days.The results demon-strated that we obtained the DMT1-IRE gene.pAdEasy1-DMT1-IRE yielded a large fragment,plus a smaller fragment of 4.5 kb after digestion with Pac I.PCR confirmed pAdEasy1-DMT1-IRE contained gene DMT1-IRE,indicating the successful construction of recombi-nant adenovirus plasmid containing DMT1-IRE.GFPfluorescence further confirmed the generation of recombi-nant AdDMT1-IRE adenovirus.AdDMT1-IRE could efficiently infect C6 glioma cells.And cell viability decreased in AdDMT1-IRE infected cells after iron overload compared to the control.These results suggest that the over expressed DMT1-IRE can aggravate the iron induced cell death due to its iron influx function.